The most advanced factory for the production of wood pellets Ekoline Kovan Planning and construction of complete lines for pellet production turnkey solution.
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Process of manufacturing wood pellet
While relatively simple in concept, wood pellet manufacturing is a capital intensive undertaking, and the production of high‐quality pellets on a consistent basis takes experience and a high level of quality control. Over 20 years of work experience in pellet production projects have enabled us the possibility to offer complete solutions to our customers or solve their individual problems. Our extensive experience enables us to produce turnkey projects, but also individual solutions.
In order to simply explain the production of pellets we have singled out the following phases :
- Preparation of input raw material
- Drying of material and fine preparation
-Pelletizing
-Packing
Preparation of input raw material
In most cases, the raw material for pellet production is a byproduct of some other wood processing operation. This byproduct makes an ideal raw material for pellet production; however, as the interest in pellet production grows, some mills are generating pellet-making raw materials directly from trees (i.e. “Roundwood”),
In the most complex version of material preparation, the received wood is debarked (No) and processed in a drum chipper (No) into uniform-sized particles for drying. The bark is removed to control ash content in the final product and is usually used to fuel the dryer.
Drying of material and fine preparation
The purpose of the drying process is that the material, which has a humidity of up to 60%, drops to a level of 8-10% which enables pelleting. The content of water in the raw material must be about 10 % before the pelletizing process begins. If the content of water in the raw material is too high, it has to be dried. Drying is of high importance for the final product since raw material with a water content higher than 15 % is difficult to pelletize.
After the drying process, the material is ground in a hammer mill. The resulting wood flour is then separated in a cyclone. Grinding is necessary because the raw material, at delivery and due vacuum transport, can be very heterogeneous in size and volume (although it will typically be below -3-5 mm in diameter).
For the purpose of more stable pellet work, it is necessary to prepare the raw material to be hemogenic by volume. With a flow-through homogenizer, all wood particle sizes are uniformly distributed per volume.
Pelletizing
After the necessary preparation of the raw material, the material is transported to the conditioner, where by adding steam or water, the final preparation of raw material is done.
By adding water or steam into the material before pressing in the conditioner, the material can heat and soften lignin, which helps the mixed material to be compressed into final pellets much easier, and maintains consistent quality of the mixed material, which ensures the consistent quality of pellets. Its final purpose is to increase production capacity.
The round die pellet mill comprises a vertical ring die with rollers on the inside, applying pressure against the ring die. Material is fed from a surge bin through a variable speed conditioner above the pellet mill; the conditioned material is then fed into the door of the pellet mill. A screw auger then feeds material into the center of the pellet mill chamber. Inside the chamber the rollers are stationary and the die is driven. Once in the chamber, the material is taken up by the rotating die and then compressed by the rollers.
Packing
When the pellets leave the pellet mill, they are very hot, soft and releasing moisture. Before the pellets can be used or stored they must first be left to cool and dry. As the pellet mill compresses the raw material into pellets some material is not compressed into pellets, so that sieving is necessary.
Once the pellets have been cooled, sieved and are of sufficient quality, the pellets are ready to be packaged, stored and sold. How the pellets are packaged and stored again depends on the target market. Pellets must be protected from moisture and breakage. If moisture comes into contact with the pellets, the pellets will absorb the moisture and expand, which makes them useless.
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